arch/powerpc/platforms/powernv/opal-tracepoints.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/percpu.h>
   3 #include <linux/jump_label.h>
   4 #include <asm/trace.h>
   5
   6 #ifdef CONFIG_JUMP_LABEL
   7 struct static_key opal_tracepoint_key = STATIC_KEY_INIT;
   8
   9 int opal_tracepoint_regfunc(void)
  10 {
  11         static_key_slow_inc(&opal_tracepoint_key);
  12         return 0;
  13 }
  14
  15 void opal_tracepoint_unregfunc(void)
  16 {
  17         static_key_slow_dec(&opal_tracepoint_key);
  18 }
  19 #else
  20 /*
  21  * We optimise OPAL calls by placing opal_tracepoint_refcount
  22  * directly in the TOC so we can check if the opal tracepoints are
  23  * enabled via a single load.
  24  */
  25
  26 /* NB: reg/unreg are called while guarded with the tracepoints_mutex */
  27 extern long opal_tracepoint_refcount;
  28
  29 int opal_tracepoint_regfunc(void)
  30 {
  31         opal_tracepoint_refcount++;
  32         return 0;
  33 }
  34
  35 void opal_tracepoint_unregfunc(void)
  36 {
  37         opal_tracepoint_refcount--;
  38 }
  39 #endif
  40
  41 /*
  42  * Since the tracing code might execute OPAL calls we need to guard against
  43  * recursion.
  44  */
  45 static DEFINE_PER_CPU(unsigned int, opal_trace_depth);
  46
  47 void __trace_opal_entry(unsigned long opcode, unsigned long *args)
  48 {
  49         unsigned long flags;
  50         unsigned int *depth;
  51
  52         local_irq_save(flags);
  53
  54         depth = this_cpu_ptr(&opal_trace_depth);
  55
  56         if (*depth)
  57                 goto out;
  58
  59         (*depth)++;
  60         preempt_disable();
  61         trace_opal_entry(opcode, args);
  62         (*depth)--;
  63
  64 out:
  65         local_irq_restore(flags);
  66 }
  67
  68 void __trace_opal_exit(long opcode, unsigned long retval)
  69 {
  70         unsigned long flags;
  71         unsigned int *depth;
  72
  73         local_irq_save(flags);
  74
  75         depth = this_cpu_ptr(&opal_trace_depth);
  76
  77         if (*depth)
  78                 goto out;
  79
  80         (*depth)++;
  81         trace_opal_exit(opcode, retval);
  82         preempt_enable();
  83         (*depth)--;
  84
  85 out:
  86         local_irq_restore(flags);
  87 }